Halogenated alkyl phosphates are chemicals that are widely used in our environment and are structurally related to several synthetic male antifertility agents. Tris (2,3-dibromopropyl) phosphate (Tris-BP) and tris (1,3-dichloro-2-propyl) phosphate (Tris-CP) are flame retardants whose use in clothing was discontinued when Tris-BP was found to be mutagenic. Tris-CP is less mutagenic and is still used as a flame retardant in polyurethane foams. Both agents are readily absorbed through the skin and Tris-CP has recently been detected in the semen of several male college students. Because of the potential genotoxic effects of these agents, the metabolism of Tris-BP and Tris-CP will be examined with reference to toxicity in order to better determine the nature of the reactive metabolites that are formed. The enzymes responsible for Tris-CP mutagenicity will be examined in the Ames/microsome bacterial mutagenesis assay to determine requirements for mutagenicity as we previously reported for Tris-BP. Specifically deuterated analogs of Tris-BP and Tris-CP will be prepared to compare their mutagenic potential to the unlabeled substrates in an attempt to determine those sites of metabolism that lead to potentially toxic or non-toxic metabolites. Suspected metabolites of Tris-BP and Tris-CP will be synthesized in order to test their genotoxic potential and to investigate metabolite profiles of Tris-BP and Tris-CP in male Wistar rats, a strain that is susceptible to both the genotoxic and directly cytotoxic effects of Tris-BP. HPLC will be used to separate metabolites, and either GC-MS or direct probe insertion MS will be used to structurally identify metabolites. Radiolabeled analogs of Tris-BP and Tris-CP will be prepared to aid both in following the course of metabolism and in determining the nature of adducts formed with DNA and glutathione. Finally (1,2-dibromo-2,2-dichloroethyl) dimethyl phosphate (Naled) will be tested for genotoxic potential in several short-term bioassay systems inlcuding bacterial mutagenesis, DNA repair, and cell transformation assays. Naled is a widely used pesticide found in several preparations for controlling flea and tick populations in domestic animals. If this pesticide proves to be mutagenic, future work will be directed towards clarifying whether or not a problem exists with regard to its widespread use.